Tools to limit inbreeding

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Most producers know that high levels of inbreeding have a negative impact. Research has shown a decrease in milk production, reproductive health and an increase in the mortality of offspring. And, most producers know that evaluating pedigrees on individual matings – ideally done with computers – is the best way to minimize the effects of inbreeding.

But, what do you do when you purchase unidentified animals and pedigree information is not available? The USDA's Animal Improvement Programs Laboratory (AIPL) has come up with an answer to that question. Based on what is known about a bull's inbreeding and the makeup of a breed, researchers can now estimate inbreeding depression for potential sires.

The calculation, says Lori Smith, dairy scientist at USDA-AIPL, relays information regarding a bull's relationship to the breed. "A high relationship to the breed means the ancestry of the bull is found more frequently in the population than another animal's ancestry," adds Bennet Cassell, dairy geneticist at Virginia Tech. Breeding a bull with a high relationship to the breed to an unidentified animal increases the likelihood that an unacceptable amount of inbreeding will result.

The average expected inbreeding percentage for the Holstein population is around 4.8 percent. Bulls with higher percentages would be more likely to produce an animal with a higher level of inbreeding. "If the parentage of a heifer is unknown, I would recommend breeding from bulls with 3.5 percent or less expected inbreeding," says Cassell.

The table on this page, "Active bulls with highest expected inbreeding of future daughters," shows active bulls in all six breeds that have the highest future inbreeding percentages. For more complete information on specific bulls, access the USDA-AIPL's home page at: http://aipl.arsusda.gov. After reaching the page, click on the heading "genetic evaluations." Then, click on "animal query" to look at a specific bull's information.

Monitor the relationships
However, Cassell is quick to point out that using future inbreeding percentages should be your "last resort" when trying to avoid inbreeding.

"The best way to combat inbreeding is monitoring the relationship of animals in the individual mating," he says. That means knowing the animal's sire, maternal grandsire and the pedigree of the bull you're using for breeding.

If you have difficulty managing this information on your operation, consider having someone else do it for you. For example, the Holstein Association's Dairy Vision program offers services that monitor inbreeding. One of the association's 14 regional representatives can analyze your herd's records for inbreeding and also mate your animals.

"We can mate cows to keep inbreeding at the percentage the dairy producer chooses," says Dave Hollis, director of marketing and sales for the Holstein Association (HA). "If a producer already has his animals identified with the HA, we can generate specific reports regarding the inbreeding level in his herd," says Hollis. Or, if a producer's animals are not in the HA's database, information from DHI or computerized farm record-keeping systems can be used. Adding this information to the HA's database will cost $1 per animal. The cost of consulting services is $100 per hour. For more information, call the Holstein Association at (800) 952-5200 and ask to speak to a customer service representative.

If one heifer born on your farm is 25 percent inbred, the loss of milk production from that animal is around $600 over her lifetime. What if that percentage occurs in the 100 heifers you just bought?


Active bulls with highest expected inbreeding of future daughters

HOLSTEIN
•Rothrock Blackstar Loyal
Additional information: Blackstar son
7.1% expected future inbreeding
• Queens-Manor-G Rave
Additional information: Blackstar son
7.1% expected future inbreeding

JERSEY
• Mason Boomer Sooner Berretta
Additional information: Soldierboy Boomer Sooner son
9.2% expected future inbreeding
• Greenwood Poseidon
Additional information: Soldierboy Boomer Sooner son
9.2% expected future inbreeding

AYRSHIRE
• Covey-Farms Rebate
Additional information: Mar-Ral Hi Kick
7.0% expected future inbreeding
• Palmyra Luv's Regiment
Additional information: Covey-Farms Vitality Reliable son
6.9% expected future inbreeding

BROWN SWISS
• Forest Lawn Simon Jetway
Additional information: Top Acres Elegant Simon son
8.6% expected future inbreeding
• Top Acres Dotson Prophet
Additional information: K Top Acres Dotson son
7.9% expected future inbreeding

GUERNSEY
• Nells Glow Perfecto Flint
Additional information: Lily Lane Penny Perfecto son
7.8% expected future inbreeding
• Trotacre Ideal Logic
7.3% expected future inbreeding

MILKING SHORTHORN
• Dusty Glen
4.7% expected future inbreeding
• Wildwood Dusty K-Schie
4.6% expected future inbreeding
Source: USDA-AIPL. August 1998 Sire Summary information.


Bulls with largest relationship to the breed

Although most of these bulls are no longer active, many of their sons are. So, if you don't know a cow's pedigree before breeding, and you select one of these bull's sons, the rate of inbreeding will be higher than you expect.

HOLSTEIN
• Tomar Blackstar
Birth year: 1983
Active sons: 88
7.9% expected future inbreeding
• Round Oak Rag Apple Elevation
Birth year: 1965
7.7% expected future inbreeding
• Pawnee Farm Arlinda Chief
Birth year: 1962
7.6% expected future inbreeding

JERSEY
• Highland Magic Duncan
Birth year: 1980
Active sons: 6
10.9% expected future inbreeding
• Soldierboy Boomer Sooner of CJF
Birth year: 1983
Active sons: 16
9.5% expected future inbreeding
• Mason Boomer Sooner Berretta
Birth year: 1989
Active sons: 2
9.2% expected future inbreeding

AYRSHIRE
• Selwood Betty's Commander
Birth year: 1953
11.1% expected future inbreeding
• Mar-ral Hi Kick
Birth year: 1964
8.1% expected future inbreeding
• Covey-Farms Vitality Reliable
Birth year: 1984
Active sons: 2
7.7% expected future inbreeding

BROWNSWISS
• White Cloud Jason's Elegant
Birth year: 1966
Active sons: 1
7.4% expected future inbreeding
• K Top Acres Dotson
Birth year: 1982
Active sons: 4
7.2% expected future inbreeding
• Top Acres Elegant Simon
Birth year: 1979
Active sons: 6
7.2% expected future inbreeding

GUERNSEY
• Dutch Mill Telestars Fayette
Birth year: 1977
10.1% expected future inbreeding
• Maurana Wis Telestar
Birth year: 1973
9.1% expected future inbreeding
• Lily Lane Penny Perfecto
Birth year: 1984
Active sons: 3
9.1% expected future inbreeding

MILKINGSHORTHORN
• Korncrest Pacesetter
Birth year: 1974
7.4% expected future inbreeding
• Sunny View Princess' Promise
Birth year: 1960
7.3% expected future inbreeding
• Kingsdale Elegant P.S.
Birth year: 1981
6.8% expected future inbreeding

Source: USDA-AIPL. August 1998 Sire Summary information.

 



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